Orion Molecular Cloud Complex
|Molecular cloud complex|
Part of the Orion Molecular Cloud Complex, with the Great Nebula in Orion near the center, along with the Belt of Orion, and Barnard's Loop curling around the image
|Observation data: J2000.0 epoch|
|Right ascension||05h 35.3m|
|Designations||Orion Complex, Orion Cloud Complex, Orion Molecular Cloud Complex|
The Orion Molecular Cloud Complex (or, simply, the Orion Complex) is a large group of bright nebulae, dark clouds, and young stars in the Orion constellation. The cloud is between 1 500 and 1 600 light-years away, and hundreds of light-years across. Several parts of the nebula can be observed through binoculars and small telescopes, and some parts (such as the Orion Nebula) are visible to the naked eye.
The nebula is important because of its sheer size, as it spreads several degrees from Orion's Belt to his sword. It is also one of the most active regions of stellar formation visible in the night sky, and is home to both protoplanetary discs and very young stars. The nebula is bright in infrared wavelengths due to the heat-intensive processes involved in the stellar formation, though the complex contains dark nebulae, emission nebulae, reflection nebulae, and H II regions. The presence of ripples on the surface of Orion's Molecular Cloud have been discovered recently. The ripples result from the expansion of the nebulae gas over pre-existing molecular gas. 
Nebulae within the complex
The following is a list of notable nebulae within the larger nebula complex:
- The Orion Nebula, also known as M42
- M43, which is part of the Orion Nebula
- IC 434, which contains the Horsehead Nebula
- The Horsehead Nebula
- Barnard's Loop
- M78, a reflection nebula
- Orion Molecular Cloud
- Flame Nebula (NGC 2024)
- Lambda Orionis molecular ring (Sh2-264)
Also the Orion OB1 Association is part of this complex.
- "NAME ORI COMPLEX -- Cloud". SIMBAD. Retrieved 2014-03-14.
- Berné, Olivier; Marcelino, Núria; Cernicharo, José. "Waves on the surface of the Orion molecular cloud". Nature. 466 (7309): 947–949. doi:10.1038/nature09289.
- "NAME ORI MOL CLOUD -- Molecular Cloud". SIMBAD. Retrieved 2014-03-14.
- "Orion's Big Head Revealed in Infrared". www.nasa.gov. Nasa. Retrieved 24 February 2015.